People may think sumo wrestling is a sport between two big adults. But in its birthplace, hundreds of kids, whether chubby or skinny, just battled it out to win a tournament for primary school-aged children.

On Sunday, schoolboys from fourth to sixth grades participated in the 31st national Wanpaku sumo-wrestling tournament held in Tokyo, Japan, seeking sumo glory as well as confidence to go on to pursue careers as professional sumo wrestlers.

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According to Daily Mail, around 40,000 young wrestlers across the country took part in the preliminary rounds in April this year to get a final seat at Ryogoku Kokugikan, a famous wresting ring in Tokyo.

As a sport, Wanpaku Sumo is not just about defeat. It aims to foster bravery, gratitude and consideration for others to become a good member of society.

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Yet in recent years, this traditional national sport has been losing popularity among young people.

The number of the participants in Wanpaku sumo tournament, for instance, has dropped from 70,000 in 1994 to 33,000 in 2014, despite the efforts by the sumo officials such as the Japan Sumo Association and the Japan Sumo Federation, who try to get children interested in the sport through sumo classes and amateur tournaments.

Due to sumo’s rigid rules, hierarchical traditions and hard training regimes, the youth of Japan would prefer the easier national sports like kendo and judo.

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Besides, not many would like to wear loincloth rather than cool baseball jerseys.

Also, it is seldom shown on prime-time TV as the matches are often in the afternoon when most students are at school.

But the biggest concern is health. The typical daily diet for a professional sumo wrestler includes 20,000 calories, 10 times the average intake, which partially results in their life expectancy being over 10 years shorter than that of the average Japanese male.